Tinderbox Marine Reserve borders a small beach in the delightfully named Tinderbox, near Blackmans Bay about 23km south of Hobart. Strap on a snorkel and follow an underwater trail running alongside a sandstone reef not far offshore, which is marked with submerged information plates explaining the rich local ecosystem.
Bruny Island is just over 1km away across the D'Entrecasteaux Channel: locals launch their boats at Tinderbox and skim across to Dennes Point for a beach BBQ. Roaring 40s Kayaking (www.roaring40skayaking.com.au) runs day tours around this coast (adult/child $180/150) on Sundays between November and April.